diff --git a/cue/builtin_test.go b/cue/builtin_test.go
index ca22a55..5b2da99 100644
--- a/cue/builtin_test.go
+++ b/cue/builtin_test.go
@@ -305,6 +305,9 @@
 	}, {
 		test("time", `time.Time & "no time"`),
 		`_|_(error in call to time.Time: invalid time "no time")`,
+	}, {
+		test("time", `time.Unix(1500000000, 123456)`),
+		`"2017-07-14T02:40:00.000123456Z"`,
 	}}
 	for _, tc := range testCases {
 		t.Run("", func(t *testing.T) {
diff --git a/cue/builtins.go b/cue/builtins.go
index d1d288e..83e0679 100644
--- a/cue/builtins.go
+++ b/cue/builtins.go
@@ -2544,7 +2544,7 @@
 					if err != nil {
 						return "", err
 					}
-					return t.Format(time.RFC3339Nano), nil
+					return t.UTC().Format(time.RFC3339Nano), nil
 				}()
 			},
 		}, {
@@ -2555,7 +2555,7 @@
 				sec, nsec := c.int64(0), c.int64(1)
 				c.ret = func() interface{} {
 					t := time.Unix(sec, nsec)
-					return t.Format(time.RFC3339Nano)
+					return t.UTC().Format(time.RFC3339Nano)
 				}()
 			},
 		}},